Current gate driver for wide bandgap semiconductor transistor

Abstract

A gate driver has a turn-on circuit and a turn-off circuit. The turn-on circuit pulls up a gate terminal of a wide bandgap (WBG) semiconductor transistor and turns on the WBG semiconductor transistor in response to a first status of an on-off control signal. The turn-off circuit pulls down the gate terminal of the WBG semiconductor transistor and turns off the WBG semiconductor transistor in response to a second status of the on-off control signal. When the on-off control signal transits to the first status, the turn-on circuit drives the gate terminal of the WBG semiconductor transistor at a first constant driving current, and later switches to a second constant driving current. The second constant driving current is lower than the first constant driving current.

I/We claim: 
     
         1 . A current gate driver for a wide bandgap (WBG) semiconductor transistor, comprising:
 an input terminal configured to receive an on-off control signal;   an output terminal coupled to a gate terminal of the WBG semiconductor transistor;   a turn-on circuit coupled to the output terminal, to drive the WBG semiconductor transistor by providing a gate current flowing into the gate terminal of the WBG semiconductor transistor via the output terminal in response to a first status of the on-off control signal; and   a turn-off circuit coupled to the output terminal, to pull down the gate terminal of the WBG semiconductor transistor and turn off the WBG semiconductor transistor in response to a second status of the on-off control signal; wherein   when the on-off control signal transits to the first status, the turn-on circuit is configured to drive the gate terminal of the WBG semiconductor transistor at a first constant driving current first, and later switch to a second constant driving current to drive the gate terminal of the WBG semiconductor transistor, and the second constant driving current is lower than the first constant driving current.   
     
     
         2 . The current gate driver of  claim 1 , wherein the turn-on circuit is configured to set the first constant driving current via a first resistor and configured to set the second constant driving current via a second resistor. 
     
     
         3 . The current gate driver of  claim 1 , wherein after a gate voltage of the WBG semiconductor transistor is charged to a maximum value, in response to the gate current drops below a threshold, the turn-on circuit is configured to provide the second constant driving current to drive the WBG semiconductor transistor. 
     
     
         4 . The current gate driver of  claim 1 , wherein the turn-on circuit further comprises:
 a current monitoring circuit, configured to monitor the gate current, and provide a current set signal accordingly; and   a current delivering circuit coupled to a power supply, the current delivering circuit is configured to pull up the gate terminal of the WBG semiconductor transistor with one of the first constant driving current and the second constant driving current based on the current set signal and the on-off control signal.   
     
     
         5 . The current gate driver of  claim 4 , wherein when the on-off control signal transits to the first status, the current delivering circuit is configured to provide the first constant driving current to drive the gate terminal of the WBG semiconductor transistor, and then in response to the current set signal, the current delivering circuit is configured to provide the second constant driving current to drive the gate terminal of the WBG semiconductor transistor. 
     
     
         6 . The current gate driver of  claim 4 , wherein the current monitoring circuit further comprises:
 a comparison circuit, configured to receive a current sensing signal, and configured to provide the current set signal via comparing the current sensing signal with a threshold, wherein the current sensing signal is capable of reflecting dropping of the gate current.   
     
     
         7 . The current gate driver of  claim 1 , wherein the turn-on circuit further comprises:
 a first transistor having a collector coupled to a power supply, an emitter coupled to a first node, and a base coupled to the power supply through a switch, wherein the switch is turned on and off based on the on-off control signal; and   a second transistor having a collector coupled to the base of the first transistor, an emitter coupled to a second node, and a base coupled to the emitter of the first transistor at the first node; wherein   a first resistor and a second resistor are coupled between the first node and the second node, and the second node is coupled to the output terminal of the gate driver.   
     
     
         8 . The current gate driver of  claim 7 , wherein the turn-on circuit further comprises:
 a comparison circuit, configured to compare a voltage across the base and the emitter of the second transistor with a threshold, and the emitter of the first transistor and the base of the second transistor are configured to be selectively coupled to one of the first resistor and the second resistor based on a comparison result between the threshold and the voltage across the base and the emitter of the second transistor.   
     
     
         9 . A gate driving method for a wide bandgap (WBG) semiconductor transistor, comprising:
 receiving an on-off control signal;   in response to a first status of the on-off control signal, delivering a first constant driving current to a gate terminal of the WBG semiconductor transistor to turn on the WBG semiconductor transistor;   after a voltage of the gate terminal of the WBG semiconductor transistor is charged at a maximum value, automatically switching to deliver a second constant driving current to the gate terminal of the WBG semiconductor transistor to keep the WBG semiconductor activated, wherein the second constant driving current is lower than the first constant driving current; and   in response to a second status of the on-off control signal, pulling down the gate terminal of the WBG semiconductor transistor to turn off the WBG semiconductor transistor.   
     
     
         10 . The gate driving method of  claim 9 , wherein the first constant driving current is established via a first resistor, and the second constant driving current is established via a second resistor. 
     
     
         11 . The gate driving method of  claim 9 , further comprising:
 establishing the first constant driving current via a first resistor; and   when a current flowing through the gate terminal of the WBG semiconductor transistor drops below a threshold, establishing the second constant driving current via a second resistor.   
     
     
         12 . The gate driving method of  claim 9 , further comprising:
 coupling a collector of a first transistor to a power supply, and coupling a base of the first transistor to the power supply through a switch;   coupling a collector of a second transistor to the base of the first transistor, coupling a base of the second transistor to an emitter of the first transistor, and coupling an emitter of the second transistor to the gate terminal of the WBG semiconductor transistor; and   turning on and off the switch based on the on-off control signal.   
     
     
         13 . The gate driving method of  claim 12 , further comprising:
 comparing a voltage across the base and the emitter of the second transistor with a threshold; and   selectively coupling the emitter of the first transistor and the base of the second transistor to one of a first resistor and a second resistor based on a comparison result between the threshold and the voltage across the base and the emitter of the second transistor.   
     
     
         14 . A current gate driver, comprising:
 an input pin configured to receive an on-off control signal;   a power supply pin configured to coupled to a power supply; and   a first output pin and a second output pin are coupled to a gate terminal of a wide bandgap (WBG) semiconductor transistor; wherein   in response to a first status of the on-off control signal, the gate driver is configured to provide a first constant driving current via the second output pin first, and later switch to a second constant driving current via the second output pin, to drive the gate terminal of the WBG semiconductor transistor; and wherein   in response to a second status of the on-off control signal, the gate driver is configured to pull down the gate terminal of the WBG semiconductor transistor via the first output pin.   
     
     
         15 . The current gate driver of  claim 14 , further comprising:
 a third output pin coupled to the gate terminal of the WBG semiconductor transistor; wherein   the second output pin is capable of be coupled to a first resistor to establish the first constant driving current; and wherein   the third output pin is capable of be coupled to a second resistor to establish the second constant driving current.   
     
     
         16 . The current gate driver of  claim 14 , wherein the second output pin is configured to be coupled to a first resistor and a second resistor, wherein the first resistor is used to establish the first constant driving current, and the second resistor is used to establish the second constant driving current. 
     
     
         17 . The current gate driver of  claim 14 , wherein the second constant driving current is lower than the first constant driving current. 
     
     
         18 . The current gate driver of  claim 14 , further comprising:
 a first transistor having a collector coupled to the power supply, an emitter coupled to a first node, and a base coupled to the power supply through a switch, wherein the switch is turned on and off based on the on-off control signal; and   a second transistor having a collector coupled to the base of the first transistor, an emitter coupled to a second node, and a base coupled to the emitter of the first transistor at the first node; wherein   a first resistor and a second resistor are coupled between the first node and the second node, and the second node is coupled to the output terminal of the gate driver.   
     
     
         19 . The current gate driver of  claim 18 , further comprising:
 a comparison circuit, configured to compare a voltage across the base and the emitter of the second transistor with a threshold, and the emitter of the first transistor and the base of the second transistor are configured to be selectively coupled to one of the first resistor and the second resistor based on a comparison result between the threshold and the voltage across the base and the emitter of the second transistor.   
     
     
         20 . The current gate driver of  claim 14 , further comprising:
 a turn-on circuit coupled to the second output pin, to pull up the gate terminal of the WBG semiconductor transistor and turn on the WBG semiconductor transistor in response to the first status of the on-off control signal; wherein   after a gate voltage of the WBG semiconductor transistor is charged to a maximum value, in response to a current flowing through the gate terminal of the WBG semiconductor transistor drops below a threshold, the turn-on circuit is configured to provide the second constant driving current to drive the WBG semiconductor transistor.